Emacs Keys: Change Major Mode Keys

General Steps to Change Major Mode Keys

To change or add keys to a Major Mode , add a function to the major mode's Hook.

1. Find the major mode's name. [see Emacs: Find Major Mode Name]
2. Find the mode's hook name. [see Emacs: List All Hooks]
3. Add a function to the Hook .
4. The function should contain code to change key, e.g. (local-set-key (kbd "C-c C-c") #'gofmt)

Example: Add Key for Go-Mode

(defun my-golang-config ()
    "For use in `go-mode-hook'."
    (local-set-key (kbd "C-c C-c") #'gofmt)
    ;; more here
    )

(when (fboundp 'go-mode)
  (add-hook 'go-mode-hook 'my-golang-config))

Example: Create Leader Key Sequence for Org Mode

;; make org mode's keys be key sequence of single keys, start with tab.

(defvar xah-org-leader-map nil "A keymap for all `org-mode' keybinding.")

(defun xah-set-org-mode-keys ()
  "Config `org-mode'.
Created: 2024-03-03
Version: 2024-04-30"
  (progn
    (define-prefix-command 'xah-org-leader-map)

    (define-key xah-org-leader-map (kbd "TAB") #'org-cycle)

    (define-key xah-org-leader-map (kbd "SPC RET") #'org-ctrl-c-ret)
    (define-key xah-org-leader-map (kbd "SPC TAB") #'org-ctrl-c-tab)

    (define-key xah-org-leader-map (kbd "a") #'org-attach)
    (define-key xah-org-leader-map (kbd "b") #'org-backward-heading-same-level)
    (define-key xah-org-leader-map (kbd "c") #'org-ctrl-c-ctrl-c)
    (define-key xah-org-leader-map (kbd "d") #'org-deadline)
    (define-key xah-org-leader-map (kbd "e") #'org-export-dispatch)
    (define-key xah-org-leader-map (kbd "f") #'org-forward-heading-same-level)

    (define-key xah-org-leader-map (kbd "g ,") #'org-date-from-calendar)
    (define-key xah-org-leader-map (kbd "g t") #'org-insert-structure-template)
    (define-key xah-org-leader-map (kbd "g .") #'org-goto-calendar)
    (define-key xah-org-leader-map (kbd "g 6") #'org-sort)
    (define-key xah-org-leader-map (kbd "g a") #'orgtbl-ascii-plot)
    (define-key xah-org-leader-map (kbd "g g") #'org-plot/gnuplot)
    (define-key xah-org-leader-map (kbd "g m b") #'org-previous-block)
    (define-key xah-org-leader-map (kbd "g m f") #'org-next-block)
    (define-key xah-org-leader-map (kbd "g m l") #'org-insert-last-stored-link)
    (define-key xah-org-leader-map (kbd "g m w") #'org-refile-copy)
    (define-key xah-org-leader-map (kbd "g s") #'org-ctrl-c-star)

    ;; more

    )

  (define-key org-mode-map (kbd (or xah-major-leader-key "TAB")) xah-org-leader-map)

  ;;
  )

(add-hook 'org-mode-hook 'xah-set-org-mode-keys)

Modify Major Mode Keymap Directly

Alternatively, if you know the mode's keymap variable name, you can modify it directly.

(progn
  ;; modify dired keys
  (require 'dired)
  (when (boundp 'dired-mode-map)
    (define-key dired-mode-map (kbd "o") #'other-window)
    (define-key dired-mode-map (kbd "2") #'delete-window)
    (define-key dired-mode-map (kbd "3") #'delete-other-windows)
    (define-key dired-mode-map (kbd "4") #'split-window-below)
    (define-key dired-mode-map (kbd "C-o") #'find-file)))